Generally, it is illegal to buy, manufacture, import, keep for sale, expose for sale, give or lend any large-capacity magazine (able to accept more than 10 rounds) in California. However, continued possession of large-capacity magazines that you owned in California prior to January 1, 2000, or purchased during freedom week (March 29th, 2019 to April 15th, 2019), are legal provided you are not otherwise prohibited. A person prohibited from possessing firearms is also prohibited from owning or possessing any magazines or ammunition.

(Pen. Code, §§16150, subd. (b), 30305, 32310.)